This blog discusses current weather, weather prediction, climate issues, and other topics

Sunday, October 16, 2011

Is Sequim the Sunniest Place in Western Washington?

There is no more important question for sun-starved residents of western Washington.

Where can one go on a day trip and experience a lot more sun? And particularly more sun during mid-winter when eastern Washington descends into its low-cloud enshrouded gloom and cold temperatures.

This blog will reveal new information and a web site dedicated to this issue.

Most of you might be suspect the answer is the Sequim area, since it well known that Sequim and adjacent locations are in the famous Olympic rainshadow, with far lower amounts of precipitation than anywhere else west of the Cascades; typical values are around 15 inches a year compared to 37-38 inches in Seattle. And satellite imagery often shows a hole in the clouds around Sequim, particularly when the flow approaching the Olympics is from the approximately the south-southwest to southwest. Here an example from this week (Oct 10, 11 AM):

You can imagine those self-satisfied Sequim types, playing golf on one of the many local courses, smiling in satisfaction in their wise decision to move there. But is there better evidence that Sequim is a sunny place on regular basis? Perhaps sea fog sneaks in there from the Strait or something else is occurring! Well, we don't have to speculate anymore. A series of solar radiation measuring devices have now been put in around the state and today I will discuss an analysis by rainshadow enthusiast David Britton, who has created a website DEDICATED to the local rainshadow phenomenon (my kind of person!): http://www.olympicrainshadow.com/

Mr. Britton compared the solar radiation reaching three stations: Lincoln High School in Port Angeles, his home in Sequim adjacent to the Strait, and on top of the atmospheric sciences building at the UW in Seattle. He has carefully calibrated the sensors using clear days--when solar radiation should be nearly identical at these sites. Here is an example of some of his findings--comparing the number of "Mostly Sunny" skies--check his website for this definition--from September 2010 to August 2011.

Sequim has more sunny days than Seattle for all recent months except July and August. Some months, such as December 2010 and April 2011, the difference is huge (8 more days of sun per month). He also has a seasonal table that is interesting:

For mid-winter (Nov, Dec, Jan) there were 20 mostly sunny days in Sequim and 4 in Seattle, but the number of cloudy days were the same. His number of "dreary" days (very low amount of solar radiation) is far higher in Seattle (19) than Sequim (5). His web site also reveals that Port Angeles is nearly as sunny as Sequim.

If there were more solar radiation measurements on the Puget Sound eastside I suspect that Issaquah and North Bend would be pretty dark places. Perhaps we better not find out...

The rainshadow over Sequim is driven by southwesterly or south-southwesterly flow at and near crest level of the Olympics--since that direction produces downslope over Sequim and vicinity. I took a look at the upper level flow approaching the Olympics at roughly crest level (5500 ft, 850 mb) and found that there was strong SW flow during the months when Sequim was much sunnier and a lack of such flow on months in which Sequim and Seattle are about the same. During the summer, winds aloft are more northerly and thus there is little rainshadow activity at all...consistent with the above results.

Right now the Washington State Agrimet network has dozens of sites with solar radiation measurements and we should be able to create good solar radiation maps for the region. Anyway, I am going to have a student do an extensive analysis of the region radiation measurements...but I am betting Sequim holds the records for west of the Cascades

Finally, need a perfect holiday gift for the weather inclined? Sure, you could get my Northwest weather book, but I have an even better idea--a Washington weather calendar! This is a fund-raiser for the Seattle Student Chapter of the American Meteorological Society and all the profits support this good cause (KCPQ is a sponsor that is not getting any of the proceeds). Cost: $13.99.

Lots of nice pictures and packed with weather info. To order try your local bookstore or calendar shops (including the UW Bookstore) or secure it online at http://weather-calendar.com/washington/

Dog Report

Thanks for those who came out to Mountlake Terrace to search for my dog....no luck. But she is someplace...so if anyone in the area sees her (see website link on right and here)...let me know....thanks, cliff

11 comments:

Speaking of sun, to quote Ricky Ricardo in "I Love Lucy": y'all've got some 'splainin' to do. Your podcast/KPLU story on Friday was so positive about sun. Here I am at 330pm on Sunday, and just little peaks through the fog. And despite Saturday's blown forecast, y'all stuck with the same thing on Sunday. I use the web cams at Rainier and the Passes to help with my forecast. And, seeing fog at Paradise this morning (Saturday was clear), I knew we'd be lucky to see any sun Sunday. It's better to be wrong when you say it's going to rain when it doesn't. When you say it's going to be sunny, and with such confidence, and then you're wrong, people get upset. And 70 and sun on Tuesday??? I'm not holding my breath.

What a freaky coincidence! My very next blog post from our trip to Alaska and the Northwest will be focused on Sequim!www.bumblechickfood.blogspot.comWe didn't really notice any significant difference in weather, but it was only 3 days, so, not exactly a full scientific analysis.Enjoyed reading yours, though.

Years ago, I was with a friend, and we were driving to Forks. Along the way, I noticed something odd about the vegetation along the side of Hwy 101. I then announced to my friend that we were near Sequim. He then asked me what made me think that. "The grass turned brown." As soon as I said that, we saw the second sign: Welcome to Sequim.

I may be wrong but I thought the south end of Lopez Island in the San Juans was the driest place in WW? I know it is sunny here many times when it looks very cloudy and possibly raining in Sequim. Cactus grows on south Lopez and we even have some here on Blakely Is.

John Davidson raises an interesting question, whether South Lopez, or South San Juan is drier and sunnier than Sequim. I know they are close.

The National Park Service reports average annual precipitation on S. San Juan in the vicinity of American Camp of roughly 18 inches, whereas the average precipitation in central Sequim is reported as 16.51 inches by the Weather Service.

There is a precipitation table on my website if you are interested. http://www.olympicrainshadow.com/olympicrainshadowmap.html

I recorded 14.94 inches closer to Dungeness Spit last year, from Oct 2010 - Sept 2011. Port Townsend is also close in precipitation.

Sunshine is a different story; my hunch is the sunniest spot is still somewhere close to and slightly north of Sequim. If anyone has a full year of radiation data with 10 minute intervals for Lopez or San Juan, I'd love to take a look at that.

I've lived in Seattle for 15 years and it seems to me subjectively that the number of sunny/clear days is increasing. I tried to find some data on that, and am only finding averages. I saw that our rain volume is increasing (rains seem heavier to me), but is the number of clear/sunny days increasing?